- Regioselective reductions of 23-epoxy acetals with lithium aluminum hydride: A reinvestigation
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Treatment of 2,3-epoxy acetals with lithium aluminum hydride gave the corresponding 2-hydroxy acetals, instead of the previously reported 3-hydroxy acetals.
- Ferraz, Helena M. C.,Sasahara, Regina M.,Losco, Pellegrino
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- Kinetics and mechanism of bromamine-T oxidation of some cyclic ketones in acidic media
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Kinetics of the oxidation cyclopentanone and cyclohexanone by bromamine-T(BAT) have been reported in perchloric acid media. A zero order dependence to BAT and first order dependence on both ketones and hydrogen ion concentrations have been observed. Observed stoichiometry, zero effects of ionic strength of the medium and p-toluenesulphonamide (TSA) and a negative dielectric effect point to a mechanism involving acid catalysed enolisation of ketones in the slow and rate determining step, followed by its subsequent fast interaction with BAT giving corresponding 1,2-diketones as final products. A solvent isotope effect (kD2O/kH2O = 2.0-2.2 (35°), 2.1-2.3 (40°) and 2.2-2.4 (35°), 2.3-2.5 (40°) for cyclopentanone and cyclohexanone, respectively) has been observed. Various thermodynamic parameters have been computed.
- Singh, Bharat,Chand, Rajendra
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- TYK2 INHIBITORS AND USES THEREOF
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The present invention provides compounds, compositions thereof, and methods of using the same for the inhibition of TYK2, and the treatment of TYK2-mediated disorders.
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Paragraph 00826; 00827
(2018/04/27)
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- Oxone-mediated oxidative cleavage of β-keto esters and 1,3-diketones to α-keto esters and 1,2-diketones in aqueous medium
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A versatile and highly efficient method for the direct synthesis of α-keto esters and 1,2-diketones has been developed. This approach utilizes the oxidative cleavage of a variety of β-keto esters and 1,3-diketones mediated by an Oxone/aluminum trichloride system. The simple one-step oxidation reaction proceeded selectively in aqueous media to afford products in high yields, short reaction times, and environmentally benign conditions.
- Stergiou, Anastasios,Bariotaki, Anna,Kalaitzakis, Dimitris,Smonou, Ioulia
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p. 7268 - 7273
(2013/08/15)
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- Asymmetric synthesis of O-protected acyloins using enoate reductases: Stereochemical control through protecting group modification
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O-Protected cyclic acyloins were obtained in nonracemic form through asymmetric bioreduction of α,β-unsaturated alkoxy ketones by using 11 different enoate reductases from the "Old Yellow Enzyme" family. The stereochemical outcome of the biotransformation could be switched by variation of the O-protecting group or by the ring size of the substrate, which allows access to both stereoisomers in up to >97 % ee Whereas α-alkoxy enones were readily accepted as substrates, β-analogs were not converted. Overall, α-alkoxy enones represent a novel type of substrate for flavin-dependent ene-reductases. Copyright
- Winkler, Christoph K.,Stueckler, Clemens,Mueller, Nicole J.,Pressnitz, Desiree,Faber, Kurt
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supporting information; experimental part
p. 6354 - 6358
(2011/02/24)
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- Method for preparing chiral diphosphines
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The invention concerns a method for preparing a compound of formula (1) wherein: A represents naphthyl or phenyl optionally substituted; and Ar1, Ar2independently represent a saturated or aromatic carbocyclic group, optionally substituted.
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- Kinetics of edta-catalysed oxidation of some cycloalkanones by pyridinium chlorochromate
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The kinetics of oxidation of some cycloalkanones with pyridinium chlorochromate (PCC) in the presence of ethylenediaminetetraacetic acid (edta) was examined and the rate coefficients evaluated. It seems that the enol form of the cycloalkanone is the active substrate. Studies with acrylonitrile indicate the absence of a free radical pathway. The rate data are consistent with a mechanism in which the cyclic ketone complexes with the Cr(VI)-edta intermediate and the ternary complex decomposes through an intramolecular electron-transfer mechanism in a slow rate-limiting step to yield cyclohexane-1,2-dione as the main product. The addition of edta and its binding to the Cr would presumably change the redox potential of the oxidant resulting in a faster reaction. The order of reactivity, C8 > C6 > C5 > C7 is explained.
- Meenakshisundaram, Subbiah,Markkandan, Ramakrishnan
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p. 1101 - 1119
(2007/10/03)
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- Novel and catalytic oxidation of internal epoxides to α-diketones
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A catalytic system based on Bi(0)-Cu(OTf)2 is efficient for the selective one-pot oxidation of 1,2-disubstituted epoxides to α-diketones under molecular oxygen and DMSO.
- Antoniotti,Dunach
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p. 2566 - 2567
(2007/10/03)
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- Asymmetric hydrogenation method of a ketonic compound and derivative
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The present invention relates to a process for the asymmetric hydrogenation of a ketonic compound and derivative. The invention relates to the use of optically active metal complexes as catalysts for the asymmetric hydrogenation of a ketonic compound and derivative. The process for the asymmetric hydrogenation of a ketonic compound and derivative is characterized in that the asymmetric hydrogenation of said compound is carried out in the presence of an effective amount of a metal complex comprising as ligand an optically active diphosphine corresponding to one of the following formulae: STR1
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- Conformational and steric effects on the oxidation of some cyclic ketones by pyridinium fluorochromate
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The kinetics of oxidation of cyclohexanone, cyclopentanone, cycloheptanone, cyclooctanone and various alpha substituted cyclohexanones by pyridinium fluorochromate(PFC) has been followed under pseudo-first order conditions in aqueous acetic acid medium in the presence of HClO4. The reaction is first order both in oxidant and substrate. The rate increases linearly with increasing [HClO4]. The salt and solvent influences together indicate the reaction to be an ion-dipole type. The stoichiometry between the substrate and oxidant is 1:2 and the product of oxidation is 1,2-diketone. The relative reactivities of various cyclic ketones have been rationalised on the basis of conformational differences and steric factors.
- Krishna Pillay,Kasthuri
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p. 544 - 548
(2007/10/03)
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- CHEMISTRY OF α-NITROEPOXIDES: SYNTHESIS OF USEFUL INTERMEDIATES VIA NUCLEOPHILIC RING OPENING OF α-NITROEPOXIDES
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Various α-nitroepoxides are converted into corresponding 1,2-diketones via two different ways of ring opening viz. with Pd(O) and with DMSO/BF3*EtO2 (or ClSiMe3).In addition to this, a variety of nucleophiles are reacted with α-nitrocyclopentene oxide 6 and α-nitrocyclohexene oxide 7 to form the corresponding α-substituted ketones which are useful intermediates in organic synthesis.Two of the products so obtained viz. 32 and 33 are also transformed further into optically active thialactones 38 and 39 respectively via baker's yeast reduction followed by lactonisation.
- Vankar, Yashwant D.,Shah, Kavita,Bawa, Anita,Singh, Surendra P.
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p. 8883 - 8906
(2007/10/02)
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- A Facile Conversion of α-Nitroepoxides into 1,2-Diones and α-Iodoketones
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1,2-Diones and α-iodoketones have been prepared from α-nitroepoxides by treatment with DMSO/BF3*Et2O followed by Et3N and BF3*Et2O/NaI respectively.
- Vankar, Yashwant D.,Saksena, Rajendra K.,Bawa, Anita
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p. 1241 - 1244
(2007/10/02)
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- REGIOSELECTIVE REDUCTIONS OF 2,3-EPOXY ACETALS WITH ZINC-CHLOROTRIMETHYLSILANE AND LITHIUM ALUMINIUM HYDRIDE: CONVENIENT SYNTHESIS OF 1,2 AND 1,3-DIONES
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A variety of 2,3-epoxy acetals have been found to undergo regioselective reductions with zinc-chlorotrimethylsilane and lithium aluminium hydride to give 2-hydroxy and 3-hydroxy acetals respectively.Their oxidation followed by hydrolysis furnished the corresponding 1,2- and 1,3-diones in good yields.
- Vankar, Yashwant D.,Chaudhuri, Narayan C.,Rao, C. Trinadha
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p. 551 - 554
(2007/10/02)
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- Palladium(O) Catalysed Conversion of α-Nitroepoxides into 1,2-Diketones
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A variety of α-nitroepoxides have been found to undergo conversion to the corresponding 1,2-diketones with Pd(PPh3)4.Two examples form α-nitroketones instead of 1,2-diketones.
- Vankar, Yashwant D.,Singh, Surendra P.
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p. 1939 - 1942
(2007/10/02)
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- Arynic Condensatiopn of Ketone Enolates. 17. New General Access to Benzocyclobutene Derivatives
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Arynic condensation of 1,2-diketone monoketal enolates appeared to be a very simple way to synthesize benzocyclobutene derivatives.X-ray diffraction and 1H NMR spectra allowed us to determine the structure of the new compounds and to propose a mechanism concerning these condensations.Finally, during this work we devised a new and easily performed two-step synthesis of 1,2-diketones.
- Gregoire, Brigitte,Carre, Marie-Christiane,Caubere, Paul
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p. 1419 - 1427
(2007/10/02)
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- A VERY EFFICIENT PREPARATION OF 1,2-DIKETONES
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Treatment of α-thiomethylketones with CuCl2-CuO in aqueous acetone affords the corresponding 1,2-dicarbonyl compounds.
- Carre, M. C.,Caubere, P.
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p. 3103 - 3106
(2007/10/02)
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- Substituted cycloalkanediones
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Novel substituted cycloalkanediones and their use for the control of weeds.
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- Synthesis of 2-Hydroxy-3-p-tolyl-2-cyclopentenone and Its Application to Isolaurene
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2-Hydroxy-3-p-tolyl-2-cyclopentenone (7), a potential starting material for synthesis of isolaurene (1), was prepared by photolysis of 2-p-toluenesulfonyloxy-2-cyclopentenone (6).Conversion of 7 into 2,5-dimethyl-2-p-tolyl-cyclopentanone (14) was carried out as follows.Methylation of 7 with methyl iodide gave 2-methoxy-3-p-tolyl-2-cyclopentanone (9), and the treatment of (9) with methyl magnesium iodide afforded 2-methyl-5-p-tolyl-2-cyclopentenone (11).This compound was allowed to react with methyl iodide in the presence of sodium methoxide to yield 2,5-dimethyl-2-p-tolyl-4-cyclopentenone (13), the hydrogenation of which over palladium charcoal gave 14.
- Tomari, Kennosuke,Machiya, Kozo,Ichimoto, Itsuo,Ueda, Hiroo
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p. 2135 - 2138
(2007/10/02)
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